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Satellite Inquiry



Hi William, K7MT

If the satellite is a LEO (Low Earth Orbit) than you cannot use SSB for the
S band downlink because of the very high doppler at 2400 MHz

On the other side a FM satellite with S band downlink is no good because
of a single channel with the same problems of a terrestrial repeater in
general but more complicated because a automatic tracking and automatic
doppler compensation is needed for the uplink/downlink

Actually we need a simple satellite with a linear transponder to communicate
with many stations at the same time using simple ground station equipments
like we did with OSCAR-6, OSCAR-7, OSCAR-8 and the russian RS satellites
also in LEO orbit

A linear transponder with a 100 KHz or less passband would be OK

The uplink frequency in U band 70 cm is ok for CW-SSB-RTTY-SSTV

The downlink frequency in V band is OK for CW-SSB-RTTY-SSTV

The above is the old Mode-B but also reverse to uplink in V band and
downlink in U band would be OK as it would be the old Mode-J

Actually to communicate CW-SSB-RTTY-SSTV via a linear transponder we
have only AO-29 in Mode-J operational and the old OSCAR-7 in Mode-B
and Mode-A but the last one is badly functioning.

If you like the idea of a good satellite linear transponder I suggest to
look at the article " A New Transponder for Amateur Satellites" designed
by i5TDJ, Piero Moroni that was publisched in AMSAT-Newsletter june
1978

This linear transponder was succesfully tested 3 time on board of
Stratosferic Balloons fling over the Mediterranean sea from Sicily to Spain
where it was recovered but never was tested on board of an amateur satellite
so that it would be very interesting to try.

Best 73" de

i8CVS Domenico

----- Original Message -----
From: William Erhardt <k7mt@mt.net>
To: AMSATBBS <amsat-bb@amsat.org>
Sent: Monday, February 21, 2005 6:17 PM
Subject: [amsat-bb] Satellite Inquiry


> Howdy from Bill K7MT AMSAT 33461.
>
> There is a possibility that amateur repeater can be placed on a satellite
> being built by Montana State University for launch in 2006. It is in
> research stage right now so we need to put together a proposol for the
> folks
> at MSU to see if it will fit into their configuration.
>
> One question from Mike KE4AZN is which frequencies would be incorporated.
> Since we have three active FM birds V/U mode I am looking at proposing U/S
> FM or SSB   or  L/S  FM or SSB.
>
> I would like some input from the amateur community as to which mode they
> would like to see ???? If you get a chance from me an email and the team
> will look at ideas for this proposol.
>
> Looking forward to hearing from the amateur community.
>
> Cheers  Bill K7MT
> ----
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----
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